Effect Of Marginal Water Irrigation On Salinize-alkalization Of Different Soils

Based on the review of national and international research results of marginal water utilization, combined with the shortage of water resources, the large wastewater emission, the low recycle rate of recycle-water, the long time of sewage irrigation, the complex saline soils in Tianjin, a marginal water irrigation test was carried out to analysis salt transfer and its effect on different saline soil through the theoretical analysis and indoor experiment method. The results were as fo11ows:1. After the short-term irrigation, the wetting front's curve was a power function, after the long-term irrigation, the wetting front fell down like the wave. In the sand loam, the wetting front moved faster than it in the silty clay loam. After short-term irrigation, the soil water content increased with soil depth decreases, and in the surface close to the saturated water content, it close to the initial water content in the wetting front; after long irrigation, water content increased with soil depth like the waves, the water content of silty clay loam. higher than it in the sand loam.2. After irrigation, pH increased first and then decreased, andin the the wetting front reduced to the minimum. In the same soil depth, the sand loam's pH was higher than it in the silty clay loam. pH irrigated with marginal water was lower . In the 0~30cm, the long-term irrigated soil's pH is lower than the short-term irrigation, while the depth of increase of pH after the long-term irrigation was up to 150cm, is significantly deeper than the short-term irrigation's (50cm).3. After marginal water, the upper soil's salt was washed off, accumulated in the wetting front and reaches the maximum. After short-term irrigation, the silty clay loam and sand loam's depth of washed were 30~35cm and 45~50cm. After long-term irrigation, the depth were 100cm and130cm. Ultrapure water's washing result was better than marginal water, silty clay loam's washing degree and depth is better than the sand loam. The long-term irrigation's washing degree and depth was better than the short-term irrigation.4. The changes of SAR show in the surface layer SAR reduced, and then SAR increased gradually with the depth. In the same depth, the silty clay loam's SAR higher than sand loam's SAR. The SAR's reductive depth of silty clay loam is deeper than sand loam's. In the surface,after long-term irrigation, SAR's reduced degrees and depth is much lower than short-term irrigation's, especially irrigation with ultrapure water and even less than 2. After the ultrapure water irrigation, SAR's reduced the depth was deeper than the marginal water's.5. Through analyzed the changes of ESP. in the surface, ESP reduced, and then increased with soil depth increases. In the same depth, silty clay loam'sESP was higher than sand loam's, the ESP's reduced deptj of silty clay loam was deeper than the sand loam's, long-term irrigation also reduces ESP and it's depth. 6. Through analyzed the 0~30cm soil's salinization and sodicilization, after irrigation, 0~30cm soil's salinization were ameliorated. After short-term irrigation, the silty clay loam reduced to mild alkaline soil and moderate alkaline soil from the heavy alkaline soil, sand loam reduced to non-saline soil and mild alkaline soil from moderate alkaline soil. After long-term, the silty clay irrigated with ultrapure water loam reduced to non-saline soil and mild alkaline soil, the silty clay loam irrigated with marginal water reduced to mild alkaline soil and moderate alkaline soil; the sand loam reduced to non-saline soil and mild alkaline soil.7. Comprehensive comparison, if irrigated with marginal water, the sand loam's salinize-alkalization's amelioration results were better than silty clay loam's. long-term rational irrigation would be beneficial to ameliorate the soil salinize-alkalization. than short-term irrigation.